1. Field of the Invention
The present invention relates to signal generation circuitry, and more particularly to circuitry that generates signal profiles or curves guaranteed to envelop other generated signal curves even when variations of chip processing, voltage and/or temperature are included.
2. Background Information
There are circuit design problems that have been addressed by designers since electrical/electronics circuitry has existed. One such problem is found in virtually all push-pull, totem-pole or cascaded drivers where one transistor is turned on driving an output in one direction while a second transistor is turned off that had driven the output in the opposite direction. If there is an overlap where, for even a short time both transistors are on or not quite turned off, the overlap may cause a current spike that may damage the circuitry or at least cause a “glitch” on the Vcc, ground or signal leads which may lead to improper circuit operation.
There is a continuing circuit design need to turn on or off one driver reliably before turning off or on another.
In other circuit applications staggered signals are necessary to ensure proper operation. For example, where secondary clocks with well defined and repeatable positive and negative phase delays are needed. In yet other applications the present invention will find advantageous applications to correct logic malfunctions in clocked circuitry where secondary clocks, derived from a primary clock, exhibit positive and negative phase delays with respect to each other and the primary clock.
Another important problem in circuit designs, including VLSI designs, is the occurrence of glitches that routinely occur in logic circuitry. Such glitches occur where a differential delay or latency occurs in a logic chain so that there is a cross over of logic curves causing an indeterminate logic state during the cross over period that can cause logic errors. By selecting overlapping curves such glitches and the indeterminate logic states can be eliminated.
The present invention is directed to providing circuitry that provides at least two signals where one signal reliably envelops the other for positive going signals and visa-versa for negative going signals.